This invention relates to an absorbent article, such as a sanitary napkin, a baby diaper, or an adult incontinence product, having a channel. More specifically, this invention relates to an absorbent article having a channel including at least one first portion and at lease one second portion being of different compression relative to one another.
Absorbent articles, such as sanitary napkins, baby diapers, adult incontinence products are well known. Such absorbent articles have a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent core therebetween. The absorbent article is designed to absorb body fluid, such as urine and menses into the absorbent core through the topsheet. One of the important functions of the absorbent article is to absorb and hold body fluid in the absorbent core and prevent from leaking of body fluid out of the absorbent core. Therefore, the absorbent core should have enough capacity to absorb and hold body fluid. However, the wearer sometimes experiences that the body fluid leaks out of the absorbent articles and soils the wearer""s undergarment and/or cloths. The leakage of body fluid tends to happen at the longitudinal sides of the absorbent article. The lateral width of the absorbent article is typically shorter than the longitudinal length. Therefore, body fluid reaches the longitudinal sides of the absorbent article earlier than the lateral edges. Body fluid does not always reach the longitudinal side of the absorbent article before changing the absorbent article. However, the wearer still feels insecure in the absorbent article with respect to leakage of body fluid if body fluid reaches near the longitudinal side.
In order for the absorbent article to absorb body fluid effectively without leakage of body fluid out of the absorbent article, the absorbent article also should be applied closely to the wearer""s body such that the absorbent article can catch body fluid in an intended place of the absorbent article (e.g., the center of the absorbent core). For example, this can be achieved by rendering a portion of the absorbent core thick such that the absorbent core is closely disposed to the wearer""s body. However, this gives the wearer a feeling of bulkiness.
In order to address to the issue of body fluid leakage from the absorbent article, absorbent articles having a channel have been provided. The channel is formed by compressing, e.g., the topsheet side toward the absorbent core. As a result of compression, the absorbent core and the topsheet deforms such that the channel is created. Body fluid running on the topsheet flows into the channel and tends to flow along the channel rather than continuing along the topsheet. In addition, because the absorbent core is compressed, and therefore has a high density area versus the rest area of the absorbent core, body fluid flowing into the channel tends to diffuse along the high density area. Further, the absorbent article preferentially bends at the channel. Therefore, disposing the compressed channel in an appropriate position, such as along opposite longitudinal sides of the absorbent article, improves the fit of the absorbent article to the wearer""s body.
Attempts to improve a control of body fluid flow in the channel have been made. For example, there is an absorbent article having a pair of grooves being formed in a top surface of the napkin by compression-molding along longitudinal opposite sides of the napkin. Each of these grooves has lower and higher density compressed zones arranged on the bottom thereof alternatively and separately in a longitudinal direction thereof. The higher compressed zone has less height than the lower compressed zone on the bottom. Such a channel is disclosed, e.g., in JP Patent publication 97/108262-A published on Apr. 28, 1997. It is said that this structure serves to suppress a phenomenon that the quantity of body exudates once having flowed into the grooves might too rapidly spread longitudinally along the grooves and thereby prevent the longitudinal opposite side edges of the napkin as well as the wearer""s undergarments contracted by these side edges from being stained with any quantity of body exudates. However, the bottom surface of the groove has an uneven geometry due to the higher compressed zone and lower compressed zone arranged alternately in a row. Therefore, body fluid cannot travel along the bottom surface of the groove so smoothly. This tends to result in too much suppressing of body fluid flow in the groove and the groove may not work as expected initially for fluid flow in the direction of the channel.
The structural integrity of the channel formed on the absorbent article also must be maintained as long as possible over a period of use of the absorbent article. The topsheet of the channel portion is typically joined to the absorbent core by applying heat, heat and pressure, and/or adhesive between the topsheet and the absorbent core. However, the topsheet of the channel portion sometimes detaches from the absorbent core due to, e.g., peeling force added to the channel portion caused by twisting of the absorbent article. As a result, the channel loses its shape and does not work as initially expected.
Based on the foregoing, there is a need for an absorbent article having a channel, wherein the channel provides controlled, but smooth, body fluid flow in the channel. There is also a need for an absorbent article having a channel, wherein the structural integrity of the channel formed on the absorbent article is maintained as long as possible over a period of use of the absorbent article. None of the existing art provides all of the advantages and benefits of the present invention.
The present invention provides an absorbent article having a channel. The absorbent article comprises a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent core therebetween. The channel length is at least 10% of the length of the absorbent core. The channel has at least one first portion and at least one second portion being of different compression relative to one another. The first portion extends continuously along at least 30% of the length of the channel.
The present invention also provides an absorbent article having a channel. The absorbent article comprises a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent core therebetween. The channel has at least one first portion and at least one second portion being of different compression relative to one another. At least two boundaries between the first and second portions are generally linear and generally non-parallel.